Why in the News?

The Union Environment Ministry’s 2015 policy mandating the installation of Flue Gas Desulphurisation (FGD) equipment in all of India’s 537 coal-fired plants has been scrutinised by a recent study commissioned by the Office of the Principal Scientific Adviser.

About Flue Gas Desulphurisation (FGD) in Power Plants

• FGD is used to remove sulfur dioxide (SO₂) from flue gases in coal-fired power plants.
• The process involves passing exhaust gases through a scrubbing system using absorbents like ammonia, sodium sulfite, or limestone.
• Methods:
  • Wet Limestone Scrubbing: Gases pass through a scrubber tower with a slurry of water and limestone.
  • Dry Sorbent Injection: Uses a dry alkaline agent to neutralize SO₂.
  • Sea Water-Based Systems: Utilizes seawater’s natural alkalinity to absorb SO₂.
• FGD can remove up to 95% of sulfur dioxide, reducing SO₂ emissions significantly.
• Reduces sulfur emissions, major contributors to acid rain and air pollution.
• FGD Gypsum, a byproduct, can be used in industries like cement manufacturing.

Recent Study on FGD in Power Plants

• A study by NIAS critiques India’s FGD policy, recommending limited FGD installations for plants using imported or high-sulfur coal.
• 92% of coal in Indian plants has low sulfur content (0.3%-0.5%), meaning FGD may not significantly improve local air quality.
• Widespread FGD installation could increase power and water consumption, and result in 69 million tonnes of additional CO₂ emissions by 2030.
• Removing SO₂ (cooling agent) while increasing CO₂ emissions may accelerate climate change.
• Recommendations: Installing electrostatic precipitators (₹25 lakh per MW) can reduce 99% of particulate matter (PM), offering a more cost-effective and impactful solution.

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